An improved type of valve in particular for air compressors is The present invention relates to a valve of improved type, in particular for air compressors, but usable in any pumping device. This valve can conveniently be utilised both as a delivery valve and as a suction valve.
As is known, valves of the type indicated above are carried by a suitable closure plate of a cylinder within which reciprocates a piston. These valves allow the passage of a fluid through the holes formed in the plate, into or out from the cylinder according as the valve itself is a delivery or suction valve. The valves currently commercially available comprise a strip fixed centrally or at one end to the plate. These valves work on the principle of flexure of the strip which, in dependence on the stroke of the piston, alternately opens and closes the holes for the passage of fluid.
Valves currently commercially available have two serious disadvantages in that the use of these causes a loud noise and high temperatures. The noise is due to the fact that the strips vibrate because of the height to which they are caused to lift and which involves them in continuously striking on the plate and on an appropriate end stop for limiting the lifting movement. In some cases the phenomenon of resonance can also occur. In order to overcome this disadvantage some manufacturers do not install an end stop for the lifting movement, but notwithstanding this the strip whilst no longer striking at the end of its lifting movement, continues to strike upon closure. The high temperature is caused by the high friction which takes place during the passage of the fluid which takes place in turbulent flow because of the flow holes. To overcome this disadvantage some manufacturers form a plurality of flow holes in such a way as to increase the flow cross-section and also instal several valves. To carry more valves the plate must have a greater diameter and therefore it is necessary to increase the bore, and consequently to have the same capacity it is necessary at the same time to reduce the stroke. This has no effect other than to increase the overall manufacturing costs both because of the greater amount of working on the plate and because of the greater number of components utilised. In all cases the valves currently available are, for the reasons stated above, subjected to a considerable wear and therefore have a short life. This involves an increase in the costs because it is necessary very often to stop the operating the cycle of the devices in which these valves are installed to replace them.